• 
• 

Tuesday, February 28, 2012

Output Sharpening

Automate the process for best results

This Article Features Photo Zoom

5) PixelGenius output sharpening (dialog)

Until there's a truly objective way of determining output sharpening, you'll have to do a little testing yourself, but the amount of testing you'll need to do will be minimal when you use automated solutions. Why do automated solutions require a little testing? Because individuals, no matter how objective they try to be, have preferences for image sharpening characteristics, which may or may not mirror your own preferences. They have to make judgment calls and so will you. But when testing their solutions, your task is much easier. You simply raise or lower the opacity of the sharpening layers their routines create, make test prints, determine your preferred opacity, and use that setting for all of your prints. (In Lightroom, you test the four settings: None, Low, Medium and High.)

Output sharpening is the second to last thing you do to enhance an image file before printing it. As a final step, you'll probably want to carefully inspect an image at 100% magnification to make sure sharpening hasn't accentuated any minor flaws. If it has, retouch them. And print.

Almost all images can benefit from output sharpening. (Notable exceptions are images with extremely smooth or low-frequency detail, such as minimalist soft-focus fields.) With a little testing, you can determine optimum output sharpening routines for your images and taste, and automate the process, saving you time and delivering better and more consistent results.

How To Test Optimum File Resolution Of A Printer
There's a simple, but effective way to determine the optimum resolution of a printer.

First, render a number of one-pixel-wide bitmapped lines side by side at various resolutions: 90, 180, 240, 300, 360, 480, 720, etc. (If you prefer not to do this tedious work yourself, download the test files I've created on my website under Lessons > Technique > Test Files at www.johnpaulcaponigro.com.)

Second, copy and paste each line pair into a file of the same resolution with the same photographic image containing a wide range of frequencies of detail varying from smooth to highly textured.

Third, print the test files at the same size and compare them. You'll find that as resolution is reduced, the line pairs are rendered thicker, and as it increases, they're rendered thinner. The average size is the optimum resolution. The photographic image will show you the acceptable limits; a file with too little resolution will look heavy and soft, while a file with too much resolution will look light and brittle. You'll see that while there's one ideal resolution that achieves an average line width, a range of nearby resolutions will produce nearly identical results in photographic images, which means any resolution in this range produces good results.

What should you conclude from this? Don't resample your image files to achieve an optimum resolution; this will soften your image more than not meeting the ideal resolution. Instead, resample your image files only when their resolution doesn't meet or exceed this acceptable range of resolutions. Photoshop's Print dialog box will display both the physical dimensions and print resolution.

What are my recommended file resolutions? Optimum file resolution for Epson printers is 360 ppi, with a range between 240 ppi and 720 ppi. Optimum file resolution for Canon and HP printers is 300 ppi, with a range between 200 ppi and 600 ppi. But don't take my word for it. Test it!

John Paul Caponigro, author of Adobe Photoshop Master Class and the DVD series R/Evolution, is an internationally renowned fine artist, speaker and workshop leader. Get hundreds of free digital imaging lessons with his free enews Insights at www.johnpaulcaponigro.com.